There are many different display technologies available today. For example, in dot-matrix liquid crystal display (LCD) units, there is a grid of display elements pixels. In some other display modules, the display elements are made up of arrays of Light-emitting diodes (LEDs). In simpler displays, seven-segment, fourteen-segment, or sixteen-segment display units are used. There are even mechanical flip disc signs that can display images or text messages. In all the above examples, a controller is used to drive the display elements. For example, in LCDs, electronic controller driver integrated circuit (IC) is used to drive the liquid crystal display pixel on and off. This controller accepts a set of commands from a host microcontroller or processor that control the image or text to display. By tapping at the communication interface and reading the stream of commands, it is possible to deduce the image or message displayed.
In some applications, the information displayed is sensitive and it is desirable to protect the displayed information by making the communication channel between the display controller and the host controller secure, thereby making the commands incomprehensible. For example, in a payment application, by making the display unit secure, more information can be displayed and this simplifies the design of the other components. Accordingly, there is a need for a secure display module that can greatly simplify the design and reduce the cost of a secure application and products.